channeldb/options: add Options w/ functional modifiers

channeldb/options.go

@@ -0,0 +1,49 @@
+package channeldb
+
+const (
+	// DefaultRejectCacheSize is the default number of rejectCacheEntries to
+	// cache for use in the rejection cache of incoming gossip traffic. This
+	// produces a cache size of around 1MB.
+	DefaultRejectCacheSize = 50000
+
+	// DefaultChannelCacheSize is the default number of ChannelEdges cached
+	// in order to reply to gossip queries. This produces a cache size of
+	// around 40MB.
+	DefaultChannelCacheSize = 20000
+)
+
+// Options holds parameters for tuning and customizing a channeldb.DB.
+type Options struct {
+	// RejectCacheSize is the maximum number of rejectCacheEntries to hold
+	// in the rejection cache.
+	RejectCacheSize int
+
+	// ChannelCacheSize is the maximum number of ChannelEdges to hold in the
+	// channel cache.
+	ChannelCacheSize int
+}
+
+// DefaultOptions returns an Options populated with default values.
+func DefaultOptions() Options {
+	return Options{
+		RejectCacheSize:  DefaultRejectCacheSize,
+		ChannelCacheSize: DefaultChannelCacheSize,
+	}
+}
+
+// OptionModifier is a function signature for modifying the default Options.
+type OptionModifier func(*Options)
+
+// OptionSetRejectCacheSize sets the RejectCacheSize to n.
+func OptionSetRejectCacheSize(n int) OptionModifier {
+	return func(o *Options) {
+		o.RejectCacheSize = n
+	}
+}
+
+// OptionSetChannelCacheSize sets the ChannelCacheSize to n.
+func OptionSetChannelCacheSize(n int) OptionModifier {
+	return func(o *Options) {
+		o.ChannelCacheSize = n
+	}
+}